694 
PROFESSOR J. N. LOCKYER ON THE PHOTOGRAPHIC 
Wave-lengths of principal lines in spectra of Stars in Table A, sub-division 
(continued). 
a— 
1. 
2. 
4. 
5. 
Ken.sington. 
Potsdam. 
4571 (2) 
4583 (4) 
4629 (3) 
4567 (2) 
4574 (2) 
4613 (2) 
4629 (2) 
4643 (2) 
4650 (2) 
4714 (3) 
4650 (6) 
A list of the lines seen in three photographs of the spectrum of Rigel, taken at 
Potsdam, has already been published by Dr. Scheiner,'“ and, allowing for the 
difference between the Potsdam scale and that of Angstrom, which I have employed, 
there is a fair agreement between the two series of measures. 
The spectra of four typical stars of this sub-division, namely : a Cygni, /3 Orionis, 
y Orionis and ^ Orionis, are shown in Plate 27. Many of the finer lines recorded in 
the table have been obliterated in the process of reproduction, but all the more 
important lines are present. 
As far as the work has yet gone, sub-division (1) is only represented by a Cygni. 
The spectrum of this star is a very remarkable one. It shows many more lines than 
such stars as Rigel, but not nearly so many as stars which more or less resemble the 
Sun. The hydrogen lines are only of moderate thickness, and there are a few other 
strong lines, in addition to many fainter ones. On reference to Plate 27, it will be 
seen that it has many lines in common with Rigel and Bellatrix. 
The K line of calcium is common to all the stars in question, but the strong blue 
line of calcium, at X 4226, is absent. 
With the exception of the K line, the lines of hydrogen, and the high temperature 
line of magnesium, at X 4481, all the lines may be said to be at present of unknown 
origin. Some of the lines fall near lines of iron, but the absence of the strongest 
lines indicates that the close coincidences are probably accidental. 
The Spectrum of y Oriojiis. 
A very fine ]3hotograph of the spectrum of this star was taken on September 17, 
1892, with Instrument B. This shows many very fine lines in addition to those 
* ‘ Ast. Narh,’ No. 2923, p. 328. 
